Based on the unexpectedly high gain of this PI (~260), if LHO is in a position where they wish to avoid inducing this PI at any cost, without requiring to have active actuation runnning to damp it, they have some breathing room in the settings of the X-arm ring heaters (RHs) before the mode-spacing crosses the threshold of parametric gain, R > 1. Here I give a rough estimate on the magnitude these RH settings can be, whilst remaining in this "safe space", based on Diopter per Watt estimates here.

Presently modespacing for the relevant interacting mode in a well thermalised state sits at (see black curves in figures of this aLog): 5240 Hz in the 0'th FSR, and 80287 Hz in the 2'nd FSR.
To reach the condition for R > 1, modespacing can go up as high as 5244.5 Hz in the 0'th FSR, giving us 4.5 Hz of breathing room right now.

3 basic scenarios to reach that threshold:

• Only alter ITM: 0.44 W -> 0.34 W
• Only alter ETM: 1.00 W -> 0.92 W
• Alter both ETM and ITM proportionally to their impact on mode-spacing:
  • ITM: 0.44 W -> 0.39 W
  • ETM:  1.00 W -> 0.96 W

Effective PI damping actuation would relax this further.